Standard packages housing such optical components are open at the rear in order to allow a connecting edge of a printed circuit board supporting one or more optical components to protrude. This can result in the printed circuit board flexing due to lack of rigidity.
Optical components such as optical transmitters and receivers require shielding in order to reduce electromagnetic interference (EMI) entering or leaving the component. In standard package designs EMI may escape from or enter the module via the rear of the package. Another problem with standard modules is that where two or more printed circuit boards are housed in a single package, the two PCB's are connected by soldered connection pins which adds an extra step in the manufacturing process hamper any reworking that may be required.